Nature-mimicking layering with composite resins through a bio-inspired analysis: 25 years of the polychromatic technique

Objectives: For decades, the dental community has discussed which materials would be the ideal substitutes for lost tooth structure. Initially, the biomimetic approach advocated that feldspathic ceramics would be the material of choice for enamel. However, given the complexity of obtaining excellent dental technicians and the financial cost, are composite resins a suitable replacement? The optical properties with opalescence and fluorescence effects, as well as this material's high fracture toughness, indicate it as a long-lasting restorative material. However, because this material depends on the operator's expertise, knowledge of layering techniques and the selection of each material for the different layers is required. Thus, knowledge of the polychromatic technique through a bioinspired approach is necessary to obtain results of life-like restorations. This article aims to review the polychromatic layering technique (PLT), considering the optical and mechanical properties of dentin and enamel and correlating these properties with current composite resins to guide clinicians in selecting the most suitable restoratives for their clinical challenges. Clinical Considerations: The polychromatic layering technique is revisited, cross-referencing the properties of dentin and enamel with current composite resin restoratives and their biomimetic properties. The effectiveness and predictability of the PLT are corroborated in clinical cases of varying degrees of difficulty requiring different layering strategies. Conclusion: After the bio-inspired analysis, using nature as a model to be understood and followed, it is possible to note how the polychromatic technique remains current and viable in mimicking nature, providing esthetic and natural results in the layering of composite resins. Clinical Significance: Composite resins effectively replicate the optical and mechanical characteristics of natural dentin and enamel through the bioinspired approach presented by the polychromatic layering technique.